Uber-breathable sleeping bag shell for damp bag syndrome?

"Or is the shell really of no consequence because the dew point is going to be somewhere inside the insulation anyways?
"

I think this is it. Even when I vent heavily, even mostly uncovered, I can still get condensation on the inside of my TiGoat bivy. That uses pretty thin material. When hiking I've had sweat vapor condense and freeze on the outside of my fleece. Both experiences make me think it doesn't really matter about the fabric breathability unless moist air is actively and forcefully pumped out.

Also, one big problem with being super breathable is that it means the slightest breeze can knock all the heat out of your quilt. You'd have to add a bivy to stop that problem, but then you lose the benefits of a super breathable shell.

A cuben quilt can definitely make you sweaty. The learning curve can be difficult, especially on humid nights in the high 40's, low 50's where it's cold enough to want to cover up, but warm enough that you need to vent a lot. I think that even with a bivy you can vent enough to stay pretty dry unless it's extremely humid. A few weeks ago I had a difficult night staying dry the whole night. I would do fine most of the time, but then a low cloud would settle into the valley and I'd instantly be soaked. Eventually the cloud would leave and I'd dry out, but I felt horrible for a while. Still, I doubt I would've done much better in a quilt made of traditional materials.

I do get sweaty in a synthetic sleeping bag too, so in a way I like the cuben quilt better. I still get sweaty, but I don't have to worry about the quilt getting wet, heavy and smelly. My clothes still get wet and smelly, but the wet part takes care of itself pretty quick once I start hiking. The smelly…well, I'm still figuring out how to do trail laundry well enough to kill the funk.

> Or is the shell really of no consequence because the dew point is going
> to be somewhere inside the insulation anyways?
On really cold nights, it sure will.

OP comment about wind is also very true. That may be why the Pertex fabrics are so popular at the high end. :-)

> I seem to pump out a large amount of sweat when I sleep.
I suggest you are sleeping just far too hot. Try sleeping cooler: it minimises the sweating and despite all fears you will not die. Many of us deliberately sleep that way, for that reason.

Cheers

Thanks guys. Yea, forgot about that darned wind.

Roger, I've tried sleeping cooler, but the slightest draft makes me uncomfortable so I end up covering up right away. I'm not afraid of dying from a drafty bag, but I might just have to have more faith that I'll fall asleep regardless of a bit of perceived discomfort!

More experience and testing should be in my future this winter.

"…but the slightest draft makes me uncomfortable so I end up covering up right away. I'm not afraid of dying from a drafty bag…"

Drafts are no fun…

So borrow a Lighter/LessWarm bag. Keep it tight to eliminate the drafts, and then sleep cooler.

what bag are you using right now?

> but the slightest draft makes me uncomfortable
Interesting comment. Forgive me if I meander a bit.

I wonder whether the enthusiasm for bivy bags and UL tarps has led people to over-specify their bags or quilts for this very reason? I do know that in my UL tent we do NOT get bad drafts, and so we manage to sleep perhaps warmer per down-weight than most.

I wonder whether the draft-stopping properties of a tent have been badly under-rated? Of course you could use a bivy bag for this, but a bivy bag puts any condensation straight onto the outer shell of your quilt or bag, while in a tent the condensation is … miles … away. This would be consistent with our experiences.

Comments anyone?

cheers

Eric, I'm using a Marmot 15F Pinnacle. I'd get a different one if I could right now, but it's still a good bag.

Roger, that's an avenue that I'm not sure has been explored here yet. Alluded to, yes, but I can't recall a specific thread on it.

Unfortunately I have no memorable experience with solid wall tents in winter since my backpacking and BPLing coincided from the get go. Drafty shelters from the beginning.

People will talk of drafty tents as helping condensation inside the tent, but I'm not sure it has a positive effect on moisture inside the BAG, since most shells are wind resistant.

But you do have those who swear by tarps in winter and do not mention DBS (damp bag syndrome). Are they lucky? In denial? Able to manage their sleeping system much better?

what temps are you sleeping on average when you sweat travis?

the pinnacle is en rated down to 10F for the average Herr Deutchesman … lol

if yr healthier or younger … its probably even warmer for ya

roger's likely right in that youre sleeping too warm for the temp

try unzipping the bag and using it like a quilt

personally i sweat like a pig but dont worry about it too much since i use a synthetic bag …

as to tents and bivies … every alpinist or wanna be alpinist knows that when given a choice to use a tent or cave … limits condensation, its a few degrees warmer, gives wind protection, etc …

bivies are for when you dont plan to spend the night, when you cant dig a cave, when there's no room on the ledge, or when you have a synthetic bag and just wanna play tough guy

notice how even bear gryllis almost never bivies in the open in winter … well we all know he sleeps in a trailer ;)

I like to use a bivysack because it keeps out drafts. I can
sleep with my sleeping bag unzipped and used like a quilt
and the bivy keeps the bag clean and in reach but I vent
easily by just pulling part of the sleeping bag back. Unless
it is very windy or buggy, I leave my head out of the bivysack
using the gear filled hood like a big pillow.

Kind of like sleeping with a quilt at home, thermo regulation
is done by exposing various body parts from under the open
sleeping bag. The bivy keeps off the
bugs, wind and dew. If the bivy gets a bit sodden from
condensation, it is still lighter to carry than a
sodden tent.

Travis, if you're using a 15*F bag zipped up on 40-60*F summer nights… well, yeah, you're going to sleep way too warm and be drenched in sweat. Even in northern Michigan & Minnesota 3-season use a 32F* bag is usually plenty warm; if zipped up in summertime usually too hot. If you have to zip up for drafts, you need a cooler bag.

Roger, "I wonder whether the draft-stopping properties of a tent have been badly under-rated?" My experiences have been like yours. Prefer tents for draft-stopping & minimal condensation. Sounds like "draft-stopping" should lead to more condensation, but hasn't been my experience. I've also found that I'm more… aware of drafts & more occupied in minimizing them while sleeping under a tarp. I prefer a bit less futz factor in my experience & typically prefer tents.

"Travis, if you're using a 15*F bag zipped up on 40-60*F summer nights… well, yeah, you're going to sleep way too warm and be drenched in sweat."

+1

Holy Feathers Batman!

Hey guys, more good info, thanks. I reserve my Pinnacle for when temps dip below 25F. Otherwise I use my Montbell Spiral Down Hugger #3.

I tried the Pinnacle as a quilt for the first time last weekend. Temps got to 24F. This was also the first time I had a warm enough pad as well (Kookabay DAM). I had a BAIAC, but when temps got below 20-25F, the cold crept from underneath–which may explain my propensity to zip up right away.

As a quilt, I believe there was less condensation in the bag, but still there none the less. This was also my first time, so how a quilt works for me will take some more time in the field to figure out.

Hi Brad

> Prefer tents for draft-stopping & minimal condensation. Sounds like
> "draft-stopping" should lead to more condensation,

Well, there's 'ventilation', and there's 'drafts'. Different wind speeds!

All you need for good ventilation is a quite gentle movement of air through the tent to whisk away whatever moist air there is. And it is best if most of the air movement is near the top of the tent, as that's where the warm moist air will be heading. Meanwhile, I'm down below the ventilation enjoying a comfortable night.

Cheers

were u using a bivy and tarp?

and if so was there condensation on either the tarp or in the bivy?

Hi Travis

> but when temps got below 20-25F, the cold crept from underneath–which may
> explain my propensity to zip up right away.

Aha! This explains a fair bit. In really techie terms, you sleep system is unbalanced. In plain English: you need a warmer pad, which may allow a lighter bag.

24 F – that's -4.4 C. That's not even cold! Sue and I have managed at – 7 C with 550 g quilts. Granted we cheated by snuggling together, but we were OK. Ah – but we had really good 2.5 cm Thern-a-rests mats with a high R-value underneath us.

I think this is a fairly common observation: people complain of cold bags or quilts when really their problem is not enough insulation UNDER them.

Cheers

"I wonder whether the draft-stopping properties of a tent have been badly under-rated?"

Roger, I am in agreement with you, in principle and in personal practice. However, many of the lightweight tents in this corner of the globe contain too much mesh and/or have overly-elevated flies to be of sufficient value in blocking wind. My assumption is that some manufacturers have found it less of an expense to do this than to add proper vents in the fly and of course, it is one of the easier ways to trim a few grams.

Regarding: "people complain of cold bags or quilts when really their problem is not enough insulation UNDER them," I have to say "Yup. Absolutely."

In fact, it's amazing how many people I meet who try to cut weight by carrying NO pad, yet wonder why they slept cold in their warm bag.

Adequate under-insulation is key in making any sleep system work effectively or efficiently.

Edit: If you're using the bag at temps under 25, but still find that you're soaked in sweat at whatever temp you're in, then the bag is too warm for the way you're using it. Perhaps you're one of those who wear multiple layers to bed, too?

Perhaps you're one of those who wear multiple layers to bed, too?

Actually quite almost 100% opposite! I often have just the sheet on me while my fiancee is totally bundled up. I don't ever wake up sweaty at home. Though, that's not an equal comparison.

Hello and good day everyone! This is my first post on BPL, so you will have to excuse me if this is not the correct forum…. my question is this… I am wanting to build/make my own backcountry quilt (similar to the nunatak BC blanket) I live coastal B.C. Canada… same conditions as pacific northwest… any suggestions on specific shell/liner/baffle materials? Where is the best place to get said materials? Keep in mind i got a great deal on some (well lots actually-7lbs.) of Canadian hutterite white goose down-850FP… yes, i know that down is not the top choice for where i live, but again you all know the advantages of down. I need the shell material to be tough,water resistant, UV protectant, comfortable and downproof. I am leaning towards polyester microfiber… similar to what western mountaineering offers as standard on their bags. Any help on this subject would be very much appreciated on this matter… Want to use the materials to the best of their abilities. One more note- where can i find patterns for DIY sleeping bags/quilts, down jackets w/hood pants, booties etc. etc. etc. I did send Roger Caffin a e-mail and his info was helpful, but still am looking for more info…..I thank you all in advance for your knowledge and info. Jeff-westcoast hiker.

Hi Jeff,

Since you want to make your own gear, you might want to create a thread in the "Make Your Own Gear" forum under the gear section of the site. The people reading there will be better equiped to answer your questions.

Happy trails.
Eric